This is my first year with the 5:1:1 also, but from what I've read on this forum, it lasts basically 1 year.

The intended length of time is a year - or a growing season, essentially.

However, it *can* be "pressed into service" longer if needed. I have an outdoor Fern
that's been in the 5-1-1 for two years now, and the mix has not compacted. I also have
a few Maples and Buckeyes in the 5-1-1 that are going into their second year now.

Much of this depends upon how composted your bark is. I use uncomposted bark, so that buys
some extra time in the bucket, as it were. Highly composted bark will breakdown much
more rapidly, obviously.

Josh

It really depends on your personal standards. Bark breaks down at a rate about 1/4 that of peat, and when you factor in the larger particles & reduced surface area of the bark used in the gritty mix & 5:1:1 mixes, it's much slower than that. Additionally, the roots actually become a part of the soil structure & help keep plantings' soils from collapsing. Reusing a soil from one planting in another planting is different than having a plant in the same soil for more than a year. It's not expecting too much if you wanted to keep the same plant in the 5:1:1 mix for 2 years, or even 3 if the soil mass is well colonized.

I will say though that with the gritty and 5:1:1 mixes, tight roots are usually a growth/vitality limiting factor BEFORE soil collapse is an issue, which sort of makes the answer to the question moot. I'm not being smart, at all, just trying to add some perspective. ;-)

AL

Thanks for the help guys. For some odd reason I was thinking 3-6 months..

Hi Al,
I'm new to the GW forum so if my questions have been answered elsewhere, please direct me.

I would like to grow vegetable transplants in 3 and 6-packs according to organic standards in a greenhouse using your 5.1.1 mix as pine fines are readily available to me. I have 2 questions:

1) Would you recommend substituting coconut coir for the peat?
2) Can you recommend an organic slow release fertilizer that could be used in this mix so that I would not have to use a liquid solution everytime I watered (the small containers will have to be watered at least daily, sometimes multiple times).

Hey, Anndi - WELCOME!

1) Probably not. Coir's main advantage is its wetability, but it often has salinity issues as well as an extremely high K content. Its high pH also precludes using lime as a Ca/Mg source. Peat has none of these issues - and if you allow it to dry down to the point that rewetability comes to play as an issue - you already have problems anyway because you've let the medium dry down too much.

2) I can't help much with a fertilizer suggestion for you because I left organic nutritional sources behind a long time ago; that, because I found soluble fertilizers so much easier and more effective. I DO understand and respect anyone's wish to maintain an all organic ideology, but if there is a chink in your resolve, we should talk about it a little. Not wanting to bug you or offend, I'll leave initiating that conversation up to you. ;-)

AL

I'm not at all offended - it's just that I would like to be able to sell transplants to a local nursery that buys only transplants that have been grown according to organic standards.

Can you define "soluble fertilizers" for me? Is that the opposite of something granular included in the mix in order to be able to water with plain water since the cell packs dry out so quickly. It seems that watering with a liquid fertilizer solution every time the cell packs dry out would be impractical - very different from watering large containers.

Thanks so much for the info - it's exactly what I needed to proceed.

soluble means liquid right?

In this case, soluble means "dissolves in water", which generally implies that nutrient is directly/immediately available for the plant to take up. There are dry crystals or powdered fertilizers that you then mix with water (like miracle gro). The higher quality formulas with all the micronutrients included are only widely available in liquid concentrate form, for technical reasons... but powdered forms can be ordered online.

I recently read that "improperly stored" pine fines can develop a toxicity that can be fatal to plants potted in it. No explanation of proper storage was given. I have a large pile of pine fines stored in a concrete bin that I was planning to use in the 5.1.1 mix but now am concerned. Any information?

Sometimes pine bark is windrowed in huge piles. As composting begins and particles start to gas out, )2 is pushed from the internal pore spaces and the process turns anaerobic, promoting the formation of organic acids (sharp decrease in pH) as well as other toxins that can build up in the bark. You should be safe, as long as it was dry when stored, or air can get to the center of your stash. ;-)

AL

Based on your reply, my pile is safe to use. But for my education, what if the toxins have built up - is the bark useless for a potting mix or can it be recovered by perhaps turning the pile or other means?

It can be leached & allowed to partially compost with ample air and be used for the 5:1:1 mix.

Al

"Fertilizers that supply their nutrients locked in organic molecules need to rely on soil organisms to cleave hydrocarbon chains and 'unlock' the nutrients by breaking them down into elemental forms. The problem with this is, the microorganism populations you must rely on are extremely variable in containers, being greatly affected by a number of factors, among them temperature, moisture and air volumes in the soil, pH, fertility, soil type ....."
Well said.

Yes. To hold these populations of microbs to break down the organics you need soil that retains a good amount of water. And we all know the more the drainage the faster the plant grows. This is why I always have seen more results using synthetic fertilizer in potts because you can have extreme drainage not to worry about the colinies of microbs washing out.

Many thanks to both Al and TheMasterGardener1.